Objectives: To identify changes since 1994 in the prevalence of resistance to anti-HIV drugs in primary HIV-1 infections in the United Kingdom.
Design: Retrospective and prospective assessment of viruses obtained from people recently infected with HIV.
Setting: Multiple centres (patients enrolled in the UK register of seroconverters) and a single large HIV clinic (active case ascertainment).
Participants: 69 patients infected with HIV between June 1994 and August 2000.
Main outcome measures: Prevalence of key mutations associated with drug resistance in the reverse transcriptase and protease genes of HIV-1, by year of infection.
Results: Between June 1994 and August 2000, 10 (14%) of 69 newly infected patients had one or more key HIV-1 mutations associated with drug resistance. The risk of being infected with drug resistant virus increased over time (adjusted relative risk per year 1.74 (95% confidence interval 0.93 to 3.27), P=0.06). The estimated prevalence of drug resistance in those infected in 2000 was 27% (12% to 48%).
Conclusions: Transmission of drug resistant HIV-1 in the United Kingdom seems to be increasing. New approaches to encourage safer sexual behaviour in all sectors of the population are urgently needed.